Development of a resonator with automatic tuning and coupling capability to minimize sample motion noise for in vivo EPR spectroscopy

Guanglong He, Sergey Petryakov, Alexandre Samouilov, Michael Chzhan, Periannan Kuppusamy, Jay L. Zweier

Research output: Contribution to journalArticle


EPR spectroscopy has been applied to measure free radicals in vivo; however, respiratory, cardiac, and other movements of living animals are a major source of noise and spectral distortion. Sample motions result in changes in resonator frequency, Q, and coupling. These instabilities limit the applications that can be performed and the quality of data that can be obtained. Therefore, it is of great importance to develop resonators with automatic tuning and automatic coupling capability. We report the development of automatic tuning and automatic coupling provisions for a 750-MHz transversely oriented electric field reentrant resonator using two electronically tunable high Q hyperabrupt varactor diodes and feedback loops. In both moving phantoms and living mice, these automatic coupling control and automatic tuning control provisions resulted in an 8- to 10-fold increase in signal-to-noise ratio.

Original languageEnglish (US)
Pages (from-to)218-227
Number of pages10
JournalJournal of Magnetic Resonance
Issue number2
StatePublished - 2001



  • Automatic coupling
  • Automatic tuning
  • In vivo EPR
  • Spin label
  • Varactor diode

ASJC Scopus subject areas

  • Molecular Biology
  • Physical and Theoretical Chemistry
  • Spectroscopy
  • Radiology Nuclear Medicine and imaging
  • Condensed Matter Physics

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